This study was undertaken to evaluate the patency rate of radial and ulnar artery repairs performed with use of the magnification afforded by the operative microscope. Color Doppler ultrasonographic imaging was chosen as a reproducible, noninvasive technique to evaluate patency and graphically display vascular flow characteristics. Twenty-eight consecutive patients with 35 arterial injuries form the study group. Twenty-four patients with 31 arterial lacerations were available for enrollment in the protocol. Follow-up ranged from 1 to 40 months (average, 10 months). Eighteen male and six female patients sustained 13 radial and 18 ulnar artery lacerations, all sharp. Four patients required interposition vein grafting. Overall patency after repair was found to be 84%, with 82% of single vessels and 86% of double vessels patent. The patency of single vessels repaired without the use of vein grafts was 100%. These results indicate that microscope-assisted repairs of the radial and ulnar arteries remain patent at a higher rate than is commonly cited.